Various designs of baseplate accessories are available for different makes of portable power routers, which are a well known power tool for woodworking and use with equivalent wood-like materials. Different ones of these baseplate accessories are capable, individually, of expediting the routing of circles (sometimes called compass jigs), or the use of the router in situations where an extended (or irregular shaped, often a rounded triangular shape) baseplate can stabilize the router as it is moved along a margin or edge of a workpiece with a major part of the router projecting beyond any support from below. Such accessories also are available (often called table inserts) for mounting portable routers to a stand or jig whereby the router is stationary and work is guided past the router bit. However, each such accessory has, as a rule, only one use, and separate special baseplates must be interchanged to accommodate the needs of different routing tasks. Some specialty tool suppliers even offer small sheets of clear acrylic plastic, or of phenolic materials, to the end user for construction of tailor made baseplates or jigs. Thus, there is a need for a multi-purpose baseplate accessory which can assist or simplify a number of different tasks, and which can be purchased ready to use.